Ambisonics is a full-sphere surround sound technique: in addition to the horizontal plane, it covers sound sources above and below the listener. Unlike other multichannel surround formats, its transmission channels do not carry speaker signals. Instead, they contain a speaker-independent representation of a sound field called B-format, which is then decoded to the listener's speaker setup. This extra step allows the producer to think in terms of source directions rather than loudspeaker positions, and offers the listener a considerable degree of flexibility as to the layout and number of speakers used for playback.
360-degree video and virtual reality (VR) applications provide users with immersive visual experiences. In 360-degree video and VR applications, a similarly immersive audio experience typically requires more computing resources than are available to users. B-formatted ambisonic sound provides three-dimensional audio to a user with little additional computational cost. The ambisonic sound may be head-tracked so that the sound appears to originate from the same location regardless of where the user is looking.